Commercial Diets Lack Proof Of Their Long-Term Success

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Bowing to pressure from diet experts and Federal regulators, commercial diet programs are scurrying to collect data about their long-term success, data that do not now exist.

They are also putting more emphasis on programs designed to help customers keep lost pounds off -- often charging additional fees -- in the hope that when the data are collected they will help prove their programs' long-term worth.

And, just in case, they are changing their emphasis to developing healthy eating habits and the value of small weight losses.

"If diet companies publish good studies about their success rates, consumers could make informed choices before getting into a program," said Dr. Thomas A. Wadden, a weight-loss specialist at Syracuse University.

But he added, "They know there is a liability in conducting these studies, since they will probably show that patients gain significant amount of weight one year after treatment. And people will say why should I sign up for a program where most people gain a third of their weight back in a year."

Although millions of people pay billions of dollars each year for the promise of a svelte future, there is little scientific support for claims that commercial diets can provide large-scale, long-term weight loss. And there is sometimes little science in the design of their programs. Many sell prepackaged food as magic potions for reducing and still give short shrift to developing the patterns of eating and exercise that experts say are crucial in keeping weight off.

"What we have in the weight loss industry is a culture of food sale not a culture of care," said Dr. Robert Hoerr, director of medical affairs for nutrition branch of Sandoz Pharmaceuticals Minneapolis. "I don't think that most of these programs have internal expertise to measure whether they're actually being effective."

Earlier this year, when the National Institutes of Health held a conference to review the state of the art in dieting, the institute's panel of experts concluded that it "often had no data with which to answer questions about voluntary weight loss and control methods."

Of the half-dozen weight loss companies reached in an informal survey, only two, Sandoz's Optifast program and Jenny Craig Inc., provided information based on published scientific studies about dropout rates or how many people had kept weight off after one year.

The limited data suggest that many people who complete commercial diets will regain one-third of their lost weight after one year, two-thirds or more after three years and most, if not all, in three to five years. And many will not even complete the program.

In 1991, 7.9 million people enrolled in commercial weight-loss programs, generating more than $2 billion in revenue for these plans, according to John LaRosa, research director of Marketdata Enterprises, a market research company in Valley Stream, L.I., which specializes in the diet industry. This does not include people who use liquid diets like Optifast or Medifast, which must be medically supervised, he said.

The Federal Trade Commission has signed what one official called an "out of court settlement" with three major diet companies to change their advertising claims and expects to reach similar agreements with other companies in coming months. In signing these agreements, companies admit no guilt but state that they will only make claims they have data to support.

The commission decided to take action against weight-loss companies because "they were all making long-term weight loss claims and the evidence wasn't there," said Matthew Daynard, a senior lawyer with the commission.

The demand for hard numbers strikes many in the industry as unfair.

Dr. Barbara Moore of Weight Watchers, which does not keep statistics on dropout rates or long-term maintenance, said: "I take issue with their total fixation on weight in terms of pounds. Weight loss is not the only measure of success. People come out of the program healthier and more active, so they are better off. Maybe they haven't kept all their weight off, but they've started to get a handle on their eating and are exercising. How do you measure that?"

Many researchers are now convinced that "successful" diets of any kind will at best produce modest weight loss (5 to 10 percent of body weight) after one year, which must be maintained with a struggle.But doctors stress that even minor weight loss can have major health benefits.

"In the past we've asked the impossible and we didn't need to," said Dr. George Blackburn, a nutrition specialist at the New England Deaconess Hospital in Boston. "A 5 percent weight loss reduces your risk of having high blood pressure by 50 percent.

"Commercial diets don't have data to support their claims, but people who say that diets don't work don't have any data either. Diets do work, but they work in producing a 5 to 10 percent weight loss in one year. And that is something to shout about."

Dr. Wadden said: "Consumers have to realize you never lose weight once and for all. When they see that people in a program are regaining weight, well, that's to be expected. The question is how much? Are they keeping some of it off?"

To date, researchers say that the only diet program of any type that has good scientific data about its one- and two-year results is Optifast, a very low calorie liquid diet. Although Sandoz Nutrition was one of the three companies whose advertising practices were criticized by the commission, diet experts commend its Optifast program for at least opening itself to outside scientific scrutiny.

In a study by Dr. Wadden, which appeared in The Archives of Internal Medicine this May, 517 Optifast patients were followed for more than a year. About 60 percent finished the six-month weight-loss program. Among those who finished the program and returned for a one-year follow-up visit, the average client had kept off 60 percent of the lost weight. Twenty percent kept off all weight and 11 percent had gained it all back.

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Dr. Hoerr of Sandoz said he now had data showing that patients who completed the Optifast program had on average maintained 10 percent of their weight loss after two years. "I don't know what happens beyond two years, but most of the data would be pessimistic," he said.

Such statistics certainly do not show a ringing success and the true picture may be worse, because 26 percent were not weighed after one year and the researchers had no way of following dropouts, who presumably gained back most of the weight.

No one has any idea what comparable figures might be for the food-based commercial programs. In the current issue of Addictive Behaviors, a researcher who works for Jenny Craig Inc. found that among people who had completed that program, 82 percent remained within 10 percent of the weight they considered right for themselves after one year. But the chosen weight was often greater than the medically ideal weight. Also, patients reported their own weight, and the research suggested that this was routinely lower than actual weight, cutting the success rate to 64 percent.

The researcher did not study how many people dropped out of the program before achieving their desired weight loss, and only about half of the program graduates contacted to be part of the study responded.

The 1980's were a boom time for the weight-loss industry, when doctors declared that obesity was a health risk as well as a cosmetic disadvantage. A host of companies rushed in offering "cures" for the new disease.

"Five years ago, weight loss looked like a great commercial opportunity and many of these companies have brilliant marketing and spent a lot of money advertising," said Dr. Steven Heymsfield, a weight loss specialist at the St. Luke's-Roosevelt Medical Center in New York. Storefront diet programs thrived and hospitals as well as individual doctors began to offer commercial programs. They would dispense the liquid diet formulas and make money by performing required tests.

But in the last two years people have become aware that the initial weight loss is only a tiny part of the obesity problem. "It subsequently became clear that you couldn't generate a lot of money without a lot of work; that to do it properly, doctors needed the assistance of therapists and dietitians, and it would take a lot of time and not be terribly profitable," Dr. Heymsfield said. He noted that many individual doctors and hospital had since abandoned the field.

Optifast had 500 programs run out of hospital and doctors' offices in the late 1980's. Dr. Hoerr said the numbers had since dropped to the high 200's.

"What's emerged since," Dr. Heymsfield said, "is that many of these diet programs were oversold. Promises were made that couldn't be kept and risks not always disclosed. and that caught up with everyone."

Scrutiny by the Federal Trade Commission and the National Institutes of Health has already yielded some results. Many companies have been "extremely cooperative and have already changed their advertising," Mr. Daynard of the commission said. Letters of agreement between companies and the F.T.C. state that companies may advertise only claims that can be supported by scientific data. But many companies have no data and the data that exist would hardly compel a dieter to sign on.

A few companies other than Optifast say they have scientific studies in progress to evaluate success rates, but whether they will stand up to scientific scrutiny is unknown. Nutri/ System is conducting research in collaboration with scientists at a major university, said Delphine Carroll, a company spokesperson. But she would not say which university was involved or how the study was being conducted. She said the study would be submitted to a journal for peer review and she did not want to jeopardize its chance of acceptance.

Slim-Fast Foods is also conducting scientific studies on the outcome of its diet program. But sometimes the boundary between research and promotion is blurred. For example, the company also recently put the town of Pound, Wis., on a 12-week diet, culminating in makeovers for the entire village and a party at which the host, Tommy Lasorda, would congratulate each "loser" for a "weighty achievement." A public relations consultant called the effort "research."

Now that scientists are scrutinizing the problem of long-term results, diet companies are beefing up their efforts to help successful dieters maintain weight loss. But some of the maintenance programs are expensive and skeptics say dieters may be throwing good money after bad.

At Nutri/System, for example, the maintenance phase is a yearlong program involving first weekly, then monthly meetings. During the 12-month period, dieters continue to eat meals by Nutri/System, though fewer and fewer each month. Dieters receive a refund of half their maintenance fee if they are still at their desired weight after six months. They receive the remainder of the fee if still at that weight after a year.

But skeptics say such programs only artificially inflate one-year weight loss statistics because they result in an indefinite dependence on sometimes costly diet meetings and the company's prepackaged foods.

Ron Stern, president of Slim-Fast Foods, said that dieters who maintained their weight loss after an initial diet were generally those who continued to eat Slim Fast products.

Most commercial programs are also beginning to pay more attention to counseling and exercise. Scientists say that developing new habits of eating and activity is the real key to long-term maintenance -- and the only hope for breaking ties with a diet machine.

"They are trying to improve programs but it's very variable," Dr. Wadden said. "Some have lectures. But most people who are seriously overweight need more than a lecture. Most people who are seriously overweight know what they have to do -- they know they should walk more and put their fork down in between bites -- but have trouble doing it."

A front-page article last Tuesday about commercial weight-loss programs misstated the amount of weight dieters kept off two years after completing the Optifast program. It was 10 percent of their body weight, or 50 percent of their original weight loss, not 10 percent of the original loss.

A version of this article appears in print on November 24, 1992, on Page A00001 of the National edition with the headline: Commercial Diets Lack Proof Of Their Long-Term Success. Order Reprints|Today's Paper|Subscribe